Leukocytes, commonly called white blood cells, are cells that are primarily responsible for mounting an immune response by a host to pathogens and to foreign antigens. Leukocyte distribution is currently determined by simple histologic or flow cytometric assessments. These methods have significant limitations. In particular, flow cytometry is limited by the following: availability of fluorescent antibody tags, laborious nature of the antibody tagging process, and needs for separation of cells requiring large volumes of fresh cells, expensive technology as well as equipment for detection of cells, and maintaining the integrity of the outer membrane of the cells to preserve labile protein epitopes. Further limitation of methods requiring fresh cells is that the methods are not useful in situations in which prospective studies are impractical, such as in the case of rare diseases, in which large numbers of disease subjects are not available. In these cases retrospective studies are needed to correlate disease outcome with disease parameters. However, retrospective studies can be performed only if archival samples derived from archived cohort populations could be used to analyze the disease parameters. Currently there are no known methods in which archived samples from patients and normal subjects could be used to provide a quantitative estimate of leukocyte distributions in disease conditions.
Thus there is a need for methods that provide quantification of alterations in distribution of leukocytes in blood or tissues in disease conditions that do not rely upon fresh samples, that are not labor intensive and that do not use expensive technology or equipment.